Abstract Background Proteinuria is not only a biomarker of chronic kidney disease (CKD) but also a driver of CKD progression. The aim of this study was to evaluate serum and urinary tubular biomarkers in patients with biopsied proteinuric kidney disease and to correlate them with histology and kidney outcomes. Methods A single-center retrospective study was conducted on a cohort of 156 patients from January 2016 to December 2021. The following urinary and serum biomarkers were analyzed on the day of kidney biopsy: β2-mcg (beta 2 microglobulin), α1-mcg (alpha 1 microglobulin), NGAL (neutrophil gelatinase-associated lipocalin), uKIM-1 (kidney injury molecule-1), MCP-1 (monocyte chemoattractant protein-1), uDKK-3 (urinary dickkopf-3), uUMOD (uromodulin), sKIM-1 and sUMOD. A composite outcome of kidney progression or death was recorded during a median follow-up period of 26 months. Results Multivariate regression analysis identified sUMOD (beta -0.357, p<0.001) and uDKK3 (beta 0.483, p<0.001) as independent predictors of interstitial fibrosis, adjusted for age, eGFR and log proteinuria. Elevated levels of MCP-1 [OR=15.61, 95% CI (3.52-69.20)] were associated with a higher risk of cortical interstitial inflammation >10% adjusted for eGFR, log proteinuria and microhematuria. Upper tertiles of uDKK3 were associated with greater eGFR decline during follow-up. Although not a predictor of the composite outcome, doubling of uDKK3 was a predictor of kidney events (HR 2.26, 95% CI 1.04-4.94) after adjustment for interstitial fibrosis, eGFR, and proteinuria. Conclusions Tubular markers may have prognostic value in proteinuric kidney disease, correlating with specific histologic parameters and identifying cases at higher risk of CKD progression.